d, 1-propranolol was infused into salt-depleted conscious dogs at two dosages: 1 mg/kg followed by 0.60 to 0.67 mg/kg/hr, and 5 mg/kg followed by 1.57 - 1.76 mg/kg/hr. At both dosages propranolol decreased plasma renin activity (PRA), plasma aldosterone concentration, and heart rate. PRA was suppressed with the higher dosage but not with the lower dosage to values found with dietary salt loading. Mean arterial blood pressure (MABP) remained unchanged with the low-dose infusions, but decreased significantly with the high-dose infusions. The data suggest that the mechanism(s) for the increase in PRA with low-salt diets is sensitive to propranolol and that the effect of propranolol on MABP is dependent on the salt-intake and on the dose administered. BIBLIOGRAPHIC REFERENCES: Yun, J. C. H., Delea, C. S., Bartter, F.C. and Kelly, G.: Increase in renin release sinoaortic denervation and cervical vagotomy. Amer. J. Physiology 230 (3): 777-783, 1976.